These two tools were "shared-by-folder, not shared-by-use": the only live
consumer of shared/tools/{scrape_webpage,update_memory} was the main agent
(the research/memory subagents carry their own local copies; web_search,
by contrast, is genuinely shared with anonymous_chat and stays put).
Move both into main_agent/tools/ (their sole owner). The shared BUILTIN_TOOLS
catalog still lists them for action_log/revert + /agent/tools, now via
deferred-import factories (_build_scrape_webpage_tool, _build_update_memory_tool)
mirroring the create_automation precedent to avoid a multi_agent_chat import
cycle. Removed the now-dead re-exports from shared/tools/__init__.py.
Verified: full unit suite green (2431 passed, 1 skipped).